1. Field of the Invention
The present invention relates to an imaging apparatus, and more particularly, to an exit roller system for an imaging apparatus including backup rollers configured to reduce tracking.
2. Description of the Related Art
An imaging apparatus, such as a multifunction device or printer, may include an ink jet print engine that forms an image on a sheet of print media, such as paper, by ejecting ink from a plurality of ink jetting nozzles of an ink jet printhead to form a pattern of ink dots on the sheet of print media. Such an ink jet print engine typically includes a reciprocating printhead carrier that transports one or more ink jet printheads across the print medium along a bi-directional scanning path defining a print zone of the printer. Typically, the mid-frame provides media support at or near the print zone. A sheet feeding mechanism is used to advance the print medium sheet in a sheet feed direction through the print zone between scans in the main scan direction, or after all data intended to be printed with the print medium at a particular stationary position has been completed.
One such sheet feed mechanism includes a feed roller, also sometimes referred to as an index roller, and a corresponding pinch roller arrangement located upstream of the print zone, and an exit roller and corresponding backup roller arrangement, such as a plurality of star wheels, located downstream of the print zone. Efforts have been made to reduce the star wheel tracking, i.e., leaving tracks, on a printed sheet that may occur, for example, when a star wheel passes through pigmented inks used with gel based photo papers. For example, one such approach in reducing tracking is to coat the surface finish of the star wheel tips to prevent the gel coating of the photo paper from adhering to the star wheel. A second approach is to remove material from one side of the tip portions of the star wheel, such as by a chemical etch process, to reduce the contact area of the tip with respect to the sheet of print media.
What is needed in the art is a simple and cost effective backup roller design that provides reduced tracking of the backup rollers on a sheet of print media.